Seahawks season on the brink: How did it come to this?

It certainly seemed the 2014 Seahawks would be different than those teams that have made the post-Super Bowl slump a cliché.

They had locked up key players, kept their staff intact, and were still young and hyper-competitive.

Besides, they not only retained the core of an historic defense, but they were adding one of the game’s most dynamic players — a healthy Percy Harvin — to their offense.

So, if they could stay healthy, they’d be on their way to Super Bowl XLIX.

It’s all still possible as of Sunday morning. But a loss against the 9-1 Arizona Cardinals and the Seahawks would fall four games behind the leader in the NFC West, and needing five consecutive wins to get into good wild-card position.

The Seahawks are favored by a touchdown at home, despite their 6-4 record, which shows that it’s foolish to write them off yet.

But how did it reach this dramatic point so soon? How did they fall from 9-1 at this point last season?

When I asked around to coaches and players familiar with the post-Super Bowl issues before this season, they shaped a consensus on a few things.

With the Seahawks, it hasn’t seemed as if there has been any lack of effort or will to win. This team still plays hard.

What’s become clear, though, is how intensely the opponent is driven to beat the defending champs. Every week this season, the opponent has put up one of its best efforts of the year.

Nineteen regular-season and postseason games not only wears down players, but it allows those who need postseason surgery much less time to recover.

Kam Chancellor, Russell Okung, Malcolm Smith and Bruce Irvin all had surgeries in the offseason, and each has had trouble staying healthy this season, even if the issue is not the same that required surgery.

Further, key injuries deprived them of middle linebacker Bobby Wagner, who was having a Pro Bowl season, and offensive-line anchor Max Unger.

Injuries have clustered, too. Unger wasn’t the only one lost at times at center, as backups Lemuel Jeanpierre and Stephen Schilling went down, as well. And at cornerback, Byron Maxwell, Jeremy Lane and Tharold Simon all have missed significant time with injuries.

The injuries and offseason losses of some role players created a depth crisis that left the defense and special teams undermanned.

The 2013 Seahawks led the league with 39 takeaways, including a league-high 28 interceptions. They have six interceptions now.

NFL coaches aren’t stupid. Testing the Seahawks secondary with deep passes simply was not productive. Opponents completed a mere 59 percent of their passes and quarterbacks had a laughable 63.4 passer rating last season.

Teams mostly have abandoned the risky deep ball in favor of short routes and quick check-downs, with fewer interceptions and higher efficiency (65.9 percent completion). The quick routes mean quicker release and fewer sacks (Seattle is 29th in the league).

What is harder to measure is the absence of the timely big play. So common last season, it’s mostly escaped them this season.

At Kansas City last week, the Seahawks rang up touchdowns on just two of five visits inside the Chiefs’ 10-yard line.

And on defense, the numbers are worse. Their 10 opponents have gotten inside their 20 on 29 occasions, and have scored 20 touchdowns — second-highest in the NFL.

More to the point, the Seahawks, through 10 games, have already given up two more touchdowns (24) this season than through the full 16 games last season (22).

It’s not too late, of course, but there’s no margin of error. San Francisco was 6-4 this time last season and made it to the NFC title game against Seattle. But that kind of rally has to start now.

“It’s going to be a good opportunity for us to step up,” Seahawks quarterback Russell Wilson said. “We will see. The story isn’t told yet. We’re going to have to write our own story and we will see what happens.”

Yes, it’s yet to be told, but Sunday’s chapter better offer a convincing plot twist if the Seahawks are to author a happy ending.